• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8
  • Tagged with
  • 8
  • 6
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Driftoptimering av effektkondensatorbatterier och transformatorer på mottagningsstationer

Gustafsson, Stig January 2010 (has links)
Denna rapport innehåller en utredning av effektflöden på Uddevalla Energi Elnät AB:s mottagningsstationer och optimering av driftläggning för dess effektkondensatorbatterier och transformatorer. Uddevalla Energi Elnät AB har sedan 30 år haft effektkondensatorbatterier inkopplade nästan hela året och dessa behöver av åldersskäl snart bytas ut. Uddevalla Energi Elnät AB har därför behov av nya rutiner för driftläggning av effektkondensatorbatterier efter det att Svenska Kraftnät och Vattenfall AB har infört nya regler för de reaktiva effektflödena i elnätet. I utredningen om effektkondensatorbatterier har det gjorts en investeringskalkyl med tre alternativ för inköp. Alternativ 1 med central faskompensering på mottagningsstation, alternativ 2 med faskompensering på mottagningsstation kompletterat med faskompensering på abonnentstationer och alternativ 3 med lokal faskompensering på abonnentstationer.  Det framkom i utredningen att alternativ 2: Central faskompensering kompletterat med faskompensering på abonnentstationer är mest lämplig att genomföra.   Det har tidigare konstaterats att det under delar av året har varit låg belastning på några av mottagningsstationernas transformatorer. Det har aldrig utretts om det är lönsamt att stänga av den ena transformatorn under hela eller delar av året. I utredningen om driftläggning av transformatorerna på mottagningsstationerna har det beaktats tre alternativ. Ett alternativ innebär att en transformator körs i tomgång utan last och ett alternativ med en helt avstängd transformator. Det tredje alternativet är att inte göra någon förändring. I utredningen framkom det att det mest lämpliga är att inte göra någon förändring eftersom riskerna med avstängning är större än den ekonomiska vinsten på c:a 101000 SEK. / This report contains a study of power flows in Uddevalla Energi AB receiving stations and optimization of the operation control of its power capacitor batteries and transformers. For the past thirty years, Uddevalla Energi AB has employed power capacitor batteries almost all year around and these need soon to be replaced due to ageing. Uddevalla Energi Elnät AB has a need for new procedures for the operation control of the power capacitor batteries following new regulations introduced by Svenska Kraftnät and Vattenfall AB for reactive power flows on the grid. In the study of power capacitor batteries, there has been an investment calculation with three alternative purchase options. Option one is central phase compensation at the receiving station, option two is phase compensation at the receiving station supplemented with phase compensation at subscriber stations and option three is a local phase compensation at subscriber stations. The investment calculation shows that the second option: Central phase compensation supplemented with phase compensation at subscriber stations is the most favourable to implement. It has previously been found that, during certain times of the year, there has been a low load on some of the transformers of the receiving stations. It has never been investigated if it is profitable to turn off one of the transformer for the entire, or part of the year. In the investigation of the operation control of the transformers at the receiving stations, three alternatives have been considered. One alternative is that one transformer is in idle operation without load, the second alternative is that one transformer is completely turned off. The third alternative is to make no change. The study showed that the preferred alternative is to make no change, because the risks of turning off transformers are greater than the economic gain, that is approximately 101000 SEK.
2

Energikartläggning av More Biogas

Nilsson Snarberg, Isak, Petersson, Gustav January 2017 (has links)
I denna studie utförs energikartläggning av biogasanläggningen More Biogas. Anläggningens energiförbrukning kartläggs, sammanställs och visas i en modell konstruerad i Microsoft Excel. Genom att ändra frekvensen för komponenter kan modellen beräkna flöden och effektbehov i processen. För att utvärdera de resultat som modellen presenterar, testas modellen genom att anläggningens verkliga driftsituation efterliknas vid två separat tillfällen. Modellens resultat jämförs med den verkliga energiförbrukningen och avvikelser diskuteras. Ramarna för kartläggningen var att endast använda sig av enkla medel som går att hitta i de flesta verkstäder samt befintlig övervakningsutrustning.   Resultatet som presenterades av modellen gällande elförbrukningen hamnade cirka 17-25% under uppmätt elkonsumtion men då kartläggningen avgränsats i storlek är resultatet rimligt. Studien visar att energikartläggning är möjligt att utföra med enkla medel men för att avvikelser ska bli så små som möjligt krävs mer tid. / This study examines the energy consumption of the biogas production plant More Biogas. The energy usage of the facility is mapped, and the data is used to construct a model of the site in Microsoft Excel where flowrates and energy requirements are calculated based on set frequency of individual components. To see if the calculated result of the model can be considered valid, the model is tested by replicating the plants operation at two separate occasions. The result presented by the model is then compared to the actual measured energy consumption and the difference between the results is discussed. The boundaries for the mapping process was to only use the control system on site and simple tools that could be found in most workshops.   Results presented by the model concerning the electric power consumption fell short of the measured value by 17-25 % but because the energy mapping is limited in that it did not cover all the areas of the site, the results may still be considered valid. The study show that an energy mapping of an existing industrial process is possible with only simple tools but the task of making the results match real values as much as possible, requires more time.
3

Energikartläggning & optimering av energisystem : En utredning gällande förbättringsåtgärder av centralkökets energisystem vid Västerås sjukhus

Salovaara, Tom, Nordgren, Anna January 2020 (has links)
Methods for reduced energy consumption is a current subject due to ongoing climate changes and therefore a current matter in the global discussion. Policies and propositions are developed on both a global and national level, in order to decrease the overall consumption. The global target which embraces the reduction in use of energy affects industries and buildings to practice a more energy efficient usage, as well as developing efficient systems for heat recovery. This project investigates the potential in energy efficiency in a food manufacturing facility who serves Västerås central hospital. The buildings use of energy is calculated as an active heat balance, including ventilation, transmission and unintended ventilation losses. The active heat balance is used as a reference where the percentual energy reduction followed by application of the energy efficient suggestions is calculated, hence, suggestions for energy efficient actions are presented. Energy efficient and economical sustainable suggestions are developed along with the obtained information from visits on-site as well as through discussions with the operating manager. The suggestions contain operation improvements, renovation and upgrades of technical devices. The main focus of the study addressed the buildings heat consumption in both cooled and heated areas.  The suggestions were presented in terms of life cycle cost analysis to display whether the improvement is economical sustainable. It is shown that if all of the suggested improvements are implemented, the reduced energy use for heating could be decreased by 24.5 %. The economic analysis shows that all suggested actions are more cost efficient than the current building and hence considered as profitable. Discussion regarding the proposed actions and the locally developed claim for energy efficient actions were reviewed. The discussion illustrates advantages and disadvantages regarding different kind of heat exchangers as well as how additional isolation in walls affects the buildings heat balance. In conclusion, the results of the suggested actions are discussed and however they are appropriate for the investigated facility.
4

Driftoptimering av värme- och kylsystemet på Centralsjukhuset i Karlstad : Driftstrategier för perioden oktober - april

Harryson, Elise January 2022 (has links)
De förhöjda halterna av växthusgaser i luften leder till ett varmare klimat och extremväder blir vanligare,vilket är två viktiga aspekter till att minska klimatavtrycket. Region Värmland skapade 2021 en miljöplan för att minimera klimatavtrycket, använda resurserna på ett klimatsmart sätt samt bidra till en hälsosammare miljö. Studien som genomförts har studerat Centralsjukhuset i Karlstads värme- och kylanläggning som består av fyra bergvärmepumpar, två kylvärmepumpar, tre kylmaskiner, en frikylevärmeväxlare och fjärrvärme. Bergvärmepumparna är kopplade till två geolager med sammanlagt 188 vertikala borrhål. Berget som borrhålen är borrade i förväntas vara antingen granit eller gnejs som båda har en hög kvartshalt. Kvartshalten är en viktig faktor för att bestämma bergets värmeledningsförmåga som i sin tur bestämmer bergets potential att överföra värme och kyla till brinen.  Fjärrvärmen som köps in kommer från Heden i Karlstad och elen från en elmix skapad av olika energikällor både förnybara och fossila. Energiföretagen Sverige tillsammans med samarbetspartnersgenomför en miljöutvärdering utav fjärrvärmen årligen och det är fjärrvärmeutsläppen från 2019 som både Region Värmland och studien har använt för att beräkna koldioxidutsläppen fjärrvärmen ger upphov till. För beräkning av elmixens koldioxidutsläpp används Region Värmlands antagna värde som grundas i energimyndighetens siffror.  Studien som genomförts undersöker olika driftstrategier från oktober till april. En modell byggdes upp i dataprogrammet Simulink som möjliggör en dynamisk simulering över tid. Syftet med studien är att öka Region Värmlands förståelse över hur effektuttaget från bergvärmepumparna och frikylevärmeväxlaren påverkar berget med målet att ta fram olika driftstrategier för att minska både driftkostnaderna och koldioxidutsläppen för anläggningen.  Studien upptäckte att Region Värmland inte kör sitt system optimalt utan borde prioritera kylvärmepumparnas körning följt av bergvärmepumparna och fjärrvärmen. Denna prioriteringsordning skulle minska driftkostnaden från 4,6 miljoner kronor till 4,3 miljoner kronor samtidigt som det minskar koldioxidutsläppen från 218,9 ton till 179,7 ton. Om Carnotverkningsgraden skulle höjas från 0,30 till 0,35 skulle det ändra driftstrategin och det blir i stället gynnsamt att prioritera driften efter bergvärmepumparna, följt av kylvärmepumparna och sedan frikyla och fjärrvärme. Kylvärmepumparna som används på anläggningen är gamla och har därför ett lågt COP, nya kylvärmepumapar med ett COP på 5 skulle kunna minska driftkostnaden till 4,1 miljoner kronor och koldioxidutsläppen till 174,3 ton.Liknande studier som undersöker effektuttag från berg och hur bergets temperatur förändras tyder på att de finns mer att hämta från de etablerade geolagrerna. En installation av nya bergvärmepumpar med en maxeffekt på 4600 kW skulle minska driftkostnaderna till 4 miljoner kronor och koldioxidutsläppen till 162,6 ton.  Elpriset varierar årligen och en höjning på endast 0,4 kr/kWh från 1 kr/kWh till 1,4 kr/kWh medför att det blir ekonomiskt mer gynnsamt att täcka hela värmebehovet med fjärrvärme och kylbehovet med frikyla. En ökning på endast 0,4 kr/kWh är ett rimligt antagande då elen för bostäder har höjts 0,73kr/kWh på två år. / The elevated levels of greenhouse gases in the air lead to a warmer climate and extreme weather becomes more common, which are two important aspects in reducing the climate footprint. Region Värmlandcreated an environmental plan in 2021 to minimize the climate footprint, use resources in a climatesmart way and contribute to healthier environment. The study that has been carried out has studied the Central Hospital in Karlstad’s heating and cooling system consists of four geothermal heat pumps, two cooling heat pumps, three cooling machines, a free cooling heat exchanger and district heating. The geothermal heat pumps are connected to two ground sources with a total of 188 vertical boreholes. The rock on which the boreholes are drilled is expected to be either granite or gneiss, both of which have a high quartz content. Quartz content is an important factor in determining the rock’s potential to transfer heat and cold to the brine.  The district heating that is purchased comes from Heden in Karlstad and the electricity from an electricity mix created by various energy sources, both renewable and fossil. The energy companies Sverige tillsammans with partners carry out an environmental evaluation of the district heating annually and it is the district heating emissions from 2019 that both Region Värmland and the study used to calculate the carbon dioxide emissions the district heating gives rise to. For the calculation of the electricity mix’s carbon dioxide emissions, is Region Värmland assumed value used, which is based on the energy authority’s figures.  The study examines different operating strategies from October to April. A model was built in the computer program Simulink that enables a dynamic simulation over time. The purpose of the study is to increase Region Värmland’s understanding of how the power output from the geothermal heat pumpsand the free cooling heat exchanger affects the rock with the aim of developing different operating strategies to reduce both operating costs and carbon dioxide emissions for the plant.  The study discovered that Region Värmland does not run its system optimally but should prioritize the cooling heat pumps followed by the geothermal heat pumps and district heating. This prioritization scheme would reduce operating costs from 4,6 million SEK to 4,3 million SEK while reducing carbon dioxide emissions from 218,9 tons to 179,7 tons. If the Carnot efficiency were to be raised from 0,30 to 0,35, it would change the operating strategy and it would instead be favorable to prioritize the geothermal heat pumps, followed by the cooling heat pumps and then free cooling and district heating. The Cooling heat pumps used at the facility are old and therefore have a low COP, new cooling heat pumps with a COP of 5 could reduce the operating cost to 4,1 million SEK and carbon dioxide emissions to 174,3 tones. Similar studies that examine power extractions from rock and how the rock’s temperature changes indicate that there is more to be gained from the established ground sources. An installation of new geothermal heat pumps with a maximum power of 4600 kW would reduce operation costs to 4 million SEK and carbon dioxide emissions to 162,6 tones. The price of electricity varies annually and an increase of only 0,4 SEK/kWh from 1 SEK/kWh to 1,4 SEK/kWh means that it becomes more economically favorable to cover the heating needed with district heating and the cooling with free cooling. An increase of only 0,4 SEK/kWh is a reasonable assumption as electricity for homes has been increased by 0,73 SEK in two years.
5

Driftoptimering av reaktiv effekt / Reactive power optimization

Näslund, Robert January 2019 (has links)
Övik Energi Nät has an agreement with Vattenfall where Övik Energi Nät is entitled to a certain amount of generation of reactive power and a certain amount of consumption of reactive power. This agreement applies to two distribution stations located on each side of the city.This report will propose ways of how and where it is suitably to install phase compensation equipment in Övik Energis Nät, to correct the occasions when it overleaps the maximum peak allowed of reactive power.The report will also point out problems that can appear with connecting a capacitor battery and how to avoid these problems.There is a generator that generates an effect of 5 MVAr (capacitive) and at the times when the generator is not operating the reactive power overleaps the maximum peak allowed. With this knowledge there is a belief that a capacitor battery with 5 MVAr would be suitable to install to compensate when the reactive power overleaps the maximum peak allowed.
6

Projekt ringen : Potentialen av ett närvärme- och närkylanät på Akademiska sjukhusets område i Uppsala / The ring project : The impact of a local heating and cooling network at Uppsala University Hospital area

Wallgren, Philip January 2021 (has links)
Region Uppsala manages the buildings at the hospital area in Uppsala and has in recent years worked intensively with energy efficiency measures affecting the buildings, which have also yielded successful results. To continue Region Uppsala’s energy efficiency effort, Region Uppsala intends to install a local heating and cooling network for the hospital area. The intent of the local heating and cooling network is to enable the transfer of excess heat and cooling. Region Uppsala also plans to install a larger refrigerator (>1,000 kW cooling) that will provide the hospital area with cold and heat.  This project is divided into three major parts, the first part of which involves examining how much residual heat is used from the existing refrigerators in the hospital area today, and what difference the introduction of local heating and cooling networks could make regarding the use of residual heat. The second part of the project consists of investigating the impact a larger refrigerator with 4.4 MW of cooling capacity could have on the hospital area's need for district heating and district cooling. Both the difference in energy and power are investigated. The third and final part of the project consists of examining two different operating strategies for the larger refrigerator to expand its use rate. Then the dimensioning of the cooling capacity of the refrigerator is analysed for the different operating strategies.  The results of the project show that the introduction of a local heating and cooling network in the hospital area could contribute to the use of significantly more residual heat from today's existing refrigerators. Calculations show that the larger refrigerator could reduce the energy demand from both district heating and district cooling by 2,820 MWh and 7,050 MWh respectively, as well as reduce the subscribed power only from the district cooling by 3,830 kW. In addition, the analysis of the dimensioning of the larger cooling machine shows that the cooling capacity would be oversized to the cooling needs in the hospital area.
7

Energikartläggning och driftoptimering genom behovsstyrning i befintlig fastighet / Energy audit and operational optimization through demand control in existing building

Karlsson, Joakim January 2014 (has links)
Energy supply in Sweden year 2011 amounted to 577 TWh. The final energy consumption for industrial, residential and service was 379 TWh. Sweden has energy policy goals to reduce energy use in buildings. One of these goals is to reduce the energy use by 20 % in 2020 compared to the year 1995. An important step to achieve this goal is to target energy efficiency measures in existing buildings. There are also financial incentives to implement energy efficiency measures due to the fact that the cost of energy represents 30-40% of a buildings maintenance costs. In general, up to 20 % of the energy consumption can be reduced without major reconstruction. In this master thesis project presented here, an energy audit was performed and energy efficiency measures was proposed for an existing building located at Järfälla, Stockholm. The property belongs to SAAB - Defence and Security. They have an internal target to reduce energy use in their buildings with 50 % by 2015 compared to 2009. The work of this master thesis project was limited to a building locally termed hus A. This part of the property is the oldest and was built in 1968, but has expanded gradually to the year 1977. Hus A contains of offices, a production hall, laboratories and storage areas. The energy audit showed that the electricity use is far greater in hus A, compared to the an average office and administration building. This is mainly due to production processes. A breakdown of the highest electricity consumers are: Industrial processes – 61.9 kWh/m2/year Lighting – 35.7 kWh/m2/year Fans – 33.2 kWh/m2/year Refrigeration – 21.8 kWh/m2/year Compressed air – 18.9 kWh/m2/year Computer units – 7.8 kWh/m2/year Frequency converters – 4.4 kWh/m2/year Waste heat from industrial processes, primarily from the production hall leads to high cooling demand to maintain good thermal comfort. Limitations in operation control of the buildings HVAC (Heating, Cooling and Air-conditioning) systems causes high heating and cooling demand and hence the buildings thermal mass is not properly utilized. Energy saving measures was mainly focused on increasing the controlling capability of HVAC systems. By implementing the energy efficiency measures presented in this master thesis report, building thermal mass will be more efficiently utilized. In addition, end use of electricity, heat and cooling will be reduced. In total, seven energy-saving measures proposed.  One measure is implemented to prevent heating and cooling at the same time. A brief description of the energy efficiency measures and the expected result is found below. Adjust set point for TAFA301 Energy saving: 94.0 MWh/yearPayback time: 0 year Establish time schedule for compressed air systemEnergy saving: 110.8 MWh/yearPayback time: 2.5 months Demand controlled temperature set point to heating systemEnergy saving: 167.0 MWh/yearPayback time: 3.5 months Demand control of airflow in the production hallEnergy saving: 155,5 MWh/yearPayback time: 2 years and 10 months Establish time schedule for frequency invertersEnergy saving: 104.0 MWh/yearPayback time: 3 years and 2 months Radiator thermostats to the first part of the production hall Energy saving: 6.5 MWh/yearPayback time: 5 years and 2 months Demand control of airflow in conference roomsEnergy saving: 11.0 MWh/yearPayback time: 12 years and 2 months
8

Driftoptimering av kyl- och frysanläggning : En analys av en kaskadprocess med partiell förångning

Holmgren, Robin, Hallenberg, Dante January 2016 (has links)
Studien är utförd åt Freezing Food Småland Öland AB. Syftet med undersökningen var att ge förslag på åtgärder som minskar anläggningens energibehov samt att beräkna återbetalningstid för åtgärder. Genom användningen av simuleringsprogramvara tillsammans med data från praktiska mätningar så testades olika förändringar i anläggningen. Studien resulterade i förslag på en höjning av frysrumstemperaturen och temperaturen i LTB1. Dessa åtgärder höjer anläggningens köldfaktor och minskar energibehovet. Förslag för att få bukt på istillväxten är att isolera av komponenter så som rör och ventiler. Isolering ger en energibesparing och en minskad risk för korrosion. Genom belastningstester framkom det att kompressorerna arbetar ofördelaktigt så förslag på lämpliga driftområden togs fram för att öka verkningsgraden och minska underhållskostnaderna och energibehovet. Anläggningen visade sig vara väl dimensionerad mot transmissionsförluster men att golvvärmen står för en oproportionerligt stor del av förlusterna i förhållande till dess yta. / The study is conducted for Freezing Food Småland Öland AB. The purpose of the study was to propose measures to decrease the facility’s energy demand and to calculate the payback time for these suggestions. By means of using simulation software along with data from practical measurements different configurations in the facility were tested. The study resulted in suggestions consisting of an increase of the temperature in the freezing room and the temperature in LTB1.Those suggestions increases the facilities COP and decreases the energy consumption. Proposals to curb the ice growth are the insulation of components such as pipes and valves. Insulation results in a small decrease in energy demand but greatly increases the accessibility and also decreases the risk of corrosion. Through load tests conducted on the compressors it showed that the compressors were not driven in the optimal load range, suggestions were made for operation in a more favourable load range. Thus increasing the efficiency and cutting the maintenance costs. From the results it is shown that the facility is well built and dimensioned against thermal transmission. Though it turned out that the floor heating accounts for a disproportionate amount of the thermal transmission.

Page generated in 0.0626 seconds